1. Field of the Invention
The present invention relates to a cholestasis ameliorant containing tauroursodeoxycholic acid as the active ingredient. Tauroursodeoxycholic acid is a taurine conjugate of ursodeoxycholic acid represented by the following structural formula. ##STR1##
2. Background Information
Cholestasis is a pathological condition where the choleresis, which is one of the important functions of the liver, is suppressed and the bile flow from the liver through the bile duct to the duodenum is reduced, resulting in congestion of biliary components, and it is categorized into extrahepatic obstructive jaundice, which is caused by an apparent mechanical obstruction such as tumor or gallstones, and intrahepatic cholestasis, which occurs with no macroscopically noticeable site of obstruction. Intrahepatic cholestasis is further classified into acute type due to drug-induced hepatitis or viral hepatitis, chronic type represented by primary biliary cirrhosis (PBC), recurrent type occurring familially or during pregnancy and the like and the main clinical symptoms common to all types of intrahepatic cholestasis are severe jaundice and persistent itching.
Steroid and phenobarbital preparations are currently used for the treatment of intrahepatic cholestasis, showing a certain level of, but often insufficient, efficacy.
In patients with obstructive jaundice, biliary drainage techniques such as percutaneous transhepatic cholangio drainage (PTCD), whose purpose is external biliary drainage, are performed but there are quite a few cases where jaundice takes a chronic course because of insufficient biliary drainage.
Since it has recently been reported in Japan and other countries that ursodeoxycholic acid preparations have very high efficacy against intrahepatic cholestasis, development of injectable ursodeoxycholic acid preparations has been hoped for.
However, the solubility of ursodeoxycholic acid is very low and, if it is prepared in an injectable form, the injection would have shortcomings such as causing angialgia because of high pH value.
Therefore, a related substance that is soluble in water and is easy to be prepared into injectable preparations at near-neutral pH has been searched for.